Hi,
I have a logical standby database setup from primary and the standby database is a superset of primary database. We have a requirement to build another Logical standby database from the existing logical database and make the primary apply the logs to both the logical standby database. Is that is possible?

So the second standby is a standby of the first standby and not of the primary and so must be updated when the first standby is updated and not when the primary is but if your system is well tuned and configured, it is the same thing.